The present invention relates to an automatic travel guiding device for use in a vehicle, which device is capable of guiding the vehicle to travel a path tracing a target travel course preset on a road map indicated on a display screen.
Japanese Laying-open patent No. 3-231311 discloses such a conventional automatic travel guiding device that is a combination of an automatic travelling device, which is capable of controlling a vehicle to travel at a suitable running speed, tracing a road pattern in a two-dimensional plane obtained on the basis of road components extracted from a front road image taken through an image pick-up camera attached to the vehicle, and a navigation device, which is capable of guiding the vehicle to travel along a path tracing a target course preset on a road map and determining a current position of the vehicle on said road map. With this automatic travel guiding device, a road whereon the vehicle must run is recognized among the road patterns obtained from the road images taken by the pick-up camera, according to travel guiding instruction, e.g., for turning to the right or left, which was given by the navigation device, and the vehicle is controlled to follow the recognized road.
In the above-mentioned conventional system, an automatic travelling device is combined with a navigation device in such a way that the latter gives guiding information to the former. Consequently, to improve the accuracy of the automatic travel guiding device, it is necessary to separately improve the accuracy of the current position of the vehicle on the road map, which is determined by the navigation system, and the accuracy of the vehicle travel control according to road conditions (e.g., road patterns) detected from a forward extending road image taken through the pick-up camera attached to the vehicle.